A new sea level pressure record for June in Iceland

The pressure has been observed regularly in Iceland for almost 200 years. Prior to that there are gaps in the record. During the first 20 years there is only one observation per day from one station, but later the observing network became denser and more observations were made per day. From 1920 onwards use has been made of barographs to infer the variation of the pressure between readings.

Sea level pressure above 1035 hPa is not common in Iceland in the month of June and readings above 1040 hPa are exceptional, having occurred only once during the whole time of observations until past Tuesday. This occurred during the late afternoon and evening of 21 June 1939 in Stykkishólmur where 1040.4 hPa were then registered.

Last Tuesday evening the pressure rose to 1040.6 hPa at Reykjavik city airport and to slightly lower values at other stations in the vicinity. The following day the height of the 500 hPa-level over Keflavík was measured as 5870 meters, slightly above the old record height there in June, 5860 m (in June 1988). There is one slightly higher reading at 500 hPa in May 1975 over Keflavík (5880 m).

It is of interest to note that a German team of scientists made upper-air observations in Reykjavík during the spring and summer of 1939. They used a different standard atmosphere for their calculations, but after this has been amended their reading at the time of the 1939 pressure record is higher still at 500 hPa. The value in the c20v2-reanalysis (5960 m) fits well with the (amended) German ascent.

The absolute highest temperatures ever recorded in Iceland were measured during this same episode, 30.5°C at Teigarhorn at the East coast and 30.2°C at Kirkjubæjarklaustur in the SE, on 22 June 1939.

The ongoing episode has not been quite as warm as the one in 1939, the highest temperature value to the time of writing is 25.3°C - an absolute record at the station Skarðsfjöruviti (a lighthouse on the SE-coastal sands) which as been in operation since 1994.